Rod outer segment (ROS) disk membranes are being prepared in intact form by a variety of techniques. The ion permeability and membrane sidedness of these preparations are being determined. The molecular organization of the lipids and proteins in the ROS disk membrane is being studied using membrane permeable and impermeable reagents of known specificity. The topological sidedness of lipid head groups and protein peptides is being studied in these experiments. A new retinal mucopolysaccaride which holds the disks together is being studied with regard to its shape, conformation, membrane binding properties and ion exchange properties. Lipid-protein interactions in the ROS disk membrane are being studied using nuclear magnetic resonance. X-ray diffraction data on the membrane as a function of time after bleaching is being analyzed.